Script non invia mail (era "Ragazzi un aiutino.. please")

raga.. una domanda da 100.000 dollari...

ho un problema con questo codice non mi invia la mail con il codice di attivazione

mi sapreste dire il motivo? e la soluzione?

<?
/*
// 
File:            signup.php


//
*/

require_once("cms.inc.php");
//require_once("includes/auth.inc.php");

//$db = db_connect($database_host, $database_user, $database_password, $database, $database_persistent);

$_POST['l_name'] = trim($_POST['l_name']);

$validate = new Q_ValidateSignup();
$validate->ValidateSignup($_POST['l_name'], $_POST['first_name'], $_POST['last_name'], $_POST['passwd'], $_POST['passwd_verify'], $_POST['email_address'], $_POST['email_address_verify'], $_POST['disc']);

$encrypt_passwd = md5($_POST['passwd']);

if($_POST['aim'])
{
    $aim_show=1;
} 
else 
{
    $aim_show=0;
}

if($_POST['icq'])
{
    $icq_show=1;
} 
else 
{
    $icq_show=0;
}

$signed_up = time();

if ($sendmail == 1)
{
    $auth = $validate->make_confirmation_code();
}


dbn(__FILE__,__LINE__,"insert into ${db_tag}_users_accounts (login_name, passwd, auth, signed_up, first_name, last_name, email_address, aim, icq, msn, yim, country) values('$_POST[l_name]', '$encrypt_passwd', '$auth', '$signed_up', '$_POST[first_name]', '$_POST[last_name]', '$_POST[email_address]', '$_POST[aim]', '$_POST[icq]', '$_POST[msn]', '$_POST[yim]', '$_POST[country]')");
$login_id = db_insert_id();
db(__FILE__,__LINE__,"select configvalue FROM ${db_tag}_forum_config where configname='defaultusergroup' and ingame=0 limit 1");
$row = dbr();
dbn(__FILE__,__LINE__,"insert into ${db_tag}_forum_group_users (group_id, user_id, group_leader) VALUES ({$login_id}, {$row['configvalue']}, 0)");
unset($row);


if ($sendmail == 1)
{
    $headers  = "MIME-Version: 1.0\r\n";
    $headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
    $headers .= "From: $CONFIG[server_name] <$CONFIG[admin_mail]>\r\n";
    mail($_POST['email_address'], "Quantum Star SE Authorisation Code","A new account has been created on ${url_prefix} for you. \nFrom this account you may join games on the server. \nYour login name is $_POST[l_name]. \nYour Authorization code is $auth. \nYou will need it to log in the first time. \nWelcome to the Server.", $headers);
}

//insert_history($_POST['l_name'],"Created Account");

// print the page header and top table
Print_CMS_Header("Shadows Rising :: Account Created", "style01.css");

echo "Congratulations, your account has been set up.";
if ($sendMail == 1) 
{
    echo "<br>An Authorisation code has been sent to you via email. &nbsp;You will need it the first time you log in.";
}
echo "<br><a href=\"". $CONFIG['url_prefix'] ."/qcms/index.php\">Click Here</a> to return to the login page.";

print_footer();
?>